In spacecraft applications, propulsion systems based on use of a propellant substance, e.g. a gas or a liquid, are frequently utilized. An often occurring demand in this connection is to isolate a propellant supply tank for a long time, sometimes for many years, before the propellant is to be used. For instance, in applications of interplanetary space missions, the propulsion system may have to be inactive for sometimes many years until the spacecraft reaches its distant object. At that time the propulsion system must perform with full capacity and with a high degree of confidence. On micro/nano satellites, the allowed tank volume is very small and furthermore the access is limited during launch preparation, due to the normal piggy-back situation. A perfect propellant tank isolation is always highly desirable, but of outermost importance in such applications. Obviously propellant leakage must be avoided with a high degree of confidence. One way to reduce the leakage problem is to use liquid or solid propellant. However, the use of gaseous propellants or pressurized gas is in many cases necessary.
Helium is used in many bipropellant systems as pressurant gas and it has typically to be stored in high-pressure tanks. The growing use of electrical propulsion with Xenon or Krypton as propellant gas also requires leak tight high-pressure tanks. Cold gas thrusters can be used for high accuracy attitude control, in particular if spacecraft contamination is a major concern. The cold gas system uses very benign propellant gases, but requires normally high-pressure tanks to store the gas. To avoid a disturbing loss of the supply, gas or liquid, the isolation valve between the storage tank and the actual propulsion device must be absolutely leak tight. The isolation valve also has to be absolutely reliable in function when activated. This is normally solved in prior art propulsion spacecraft arrangements by use of a one-shot isolation valve, i.e. a valve that is designed for a single use. A common type in prior art is the pyro-valve.
Pyro-valves use one or several pyrotechnical charges to open a normally closed valve. The opening function is achieved either by pushing a hollow pin through a membrane, or to create a gas pressure, which in turn breaks a sealing membrane. Pyro-valves are considered hazardous because of the explosive nature of their actuation charges. This results in a need for safety precautions and thereby associated high costs. Another problem of all qualified pyrovalves in prior art is that they are very large and heavy, at least compared to a micro spacecraft. Increasing performance requirements and miniaturization demands in space technology call for new, more mass efficient, arrangements. Silicon or ceramics are in general very suitable for manufacturing spacecraft components, but the size and brittleness of such components makes the use of high energetic actuation methods such as pyrotechnical charges very difficult to use, without risking damaging the spacecraft component.
A general problem with prior art high-pressure isolation valves for single use is that they are large, heavy, expensive, hazardous and risk to damage surrounding equipment.